refactor: consolidate frontend serving and add health check

.gitea/workflows/backend.yaml

@@ -81,7 +81,7 @@ jobs:
       - name: Kontener odpowiada na API
         run: |
           docker run -d --name zyrarbot-ci -e DISCORD_TOKEN=ci-dummy zyrarbot-api:ci
-          probe="import json,urllib.request;json.load(urllib.request.urlopen('http://localhost:8000/api/status',timeout=2))"
+          probe="import json,urllib.request;json.load(urllib.request.urlopen('http://localhost:8000/api/health',timeout=2))"
           for i in $(seq 1 30); do
             if docker exec zyrarbot-ci python -c "$probe" 2>/dev/null; then
               echo "API odpowiedziało po ${i}s"